The most likely possible dangers are these: a complete collapse of Pakistani government rule that allows an extreme Islamist movement to fill the vacuum; a total loss of federal control over outlying provinces, which splinter along ethnic and tribal lines; ..."
The question: Is the clause "which splinter along ethnic and tribal lines" a description of the administrative division or the result of the loss of control? Personally I think it's the former. Thanks.
I did answer your question. That clause talks about outlying provinces.